Engine stabtee drive



April 17, 1951 2 Sheets-Sheet 1 Original Filed Oct. 28, 1948 I 3 45V %WMan R m a N INVENTOHS PAUL L. SCHNEIDER DENNIS MNIGHBEHT y HARQID .1.CHOMWEU.

1W A F 1 M \WH H a. \v v 5 m, l Ill Il-l. n 1 i Ev Qw M k w a N l 1 I 3n 1 Q R1 Rm 2 A 9.. AW Q w mw fiwvuy ll x Q l1 1; |1 QR 7 s/%k a. \m WAVW IV THEIR vATTORNEY? April 17, 1951 P. L. SCHNEIDER ET AL' 23,359ENGINE STARTER DRIVE Original Filed Opt. 28, 19 18 2 Sheets-Sheet 2 jINVENTOHS 'PAUL L. SCHNEIDER DENNIJ W. NIGHBEBT HAnoLn J. cmmwm WMwZ THE113 ATTORNEYS Reissued Apr. 17, 1951 ENGINE STARTER DRIVE Paul L.Schneider, Dennis W. Nighbert, and Harold J. Cromwell, Anderson, Ind.,assignors to General Motors Corporation, Detroit, Mich., a corporationof Delaware Original No. 2,509,110, dated May 23, 1950, Serial No.57,054, October 28, 1948. Application for reissue September 1, 1950,Serial No. 182,694

Matter enclosed in heavy brackets appears in the original patent butforms no part of this reissue specification; matter printed in italicsindicates the additions made by reissue.

2 Claims.

This invention relates to engine starter drives of the type whereinrotation of the starting motor shaft effects the meshing of the motordriven pinion with the engine flywheel gear and in which the pinion isautomatically demeshed from the flywheel gear when the engine becomesself-operative.

An object of the invention is to prevent demeshment of the pinion incase of a false start, thereby eliminating the necessity for opening thestarter switch and waiting for the starting motor to come to rest beforerepeating the starting operation.

Further objects and advantages of the present invention will be apparentfrom the following description, reference being had to the accompanyingdrawings, wherein a preferred embodiment of the present invention isclearly shown.

In the drawings: 7

Fig. 1 is a fragmentary, longitudinal, sectional view of a startingmotor equipped with a starter drive or transmission embodying thepresent invention.

Fig. 2 is a View in the direction of arrow 2 and includes a fragmentary,longitudinal, sectional view of certain parts on line 22 of Fig. 4.

Fig. 3 is a sectional view on line 33 of Fig. 1.

Fig. 4 is a view in the direction of arrow 4 of Fig. 2.

Fig. 5 is a sectional View on line 5-5 of Fig. 1.

Fig. 6 is an end view of ring 35 shown in Fig. 1.

Fig. '7 is a view in the direction of arrow 1 of Fig. 6.

Fig. 8 is in part a view in the direction of arrow 8 in Fig. 6 and inpart, a sectional view on line 8-8 of Fig. 6.

Fig. 9 is a view in the direction of arrow 9 of Fig. 8 and the partthereof in section is on the line 99 of Fig. 8.

Fig. 1D is in part a top view in the direction of arrow ID of Fig. 9,and the part thereof in section is on line Ill-l of Fig. 9.

Fig. 11 is a top view of nut 4|.

Fig. 12 is a view in the direction of arrow i2 of Fi 11.

Fig. 13 is a sectional view on line |3-|3 of Fig. 12.

Fig. 14 is a sectional view of an assembly of parts and 63.

Fig. 15 is an end view of spring 44.

Figs. 16 and 17 are views taken respectively in the direction of arrowsI6 and ll of Fig. 15.

Fig. 18 is a lan view of screw sleeve 3|, the part in section being online |8-|8 of Fig. 19.

Fig. 19 is a sectional view on line 19-43 of Fig. 18.

Fig. 20 is a sectional view on line 20-40 of Fig. 19.

Fig. 21 is a view in the direction of arrow 2| of Fig. 19.

In Fig. 1, a housing 25 which supports a motor field frame 25, isadapted to be attached to a flywheel gear housing and supports anextension 21 providing a bearing for one end of a shaft whose other endis supported by an end frame, not shown, attached to the left end offrame 26. The flywheel gear housing encloses a flywheel gear 29 which isto be connected with motor shaft 28 by the starter drive 30 whichcomprises a screw sleeve 3| (Figs. 18 through 21), which is adapted tobe supported by the shaft 28 and is secured thereto by pin 32 (Fig. 1)passing through holes 33 in the enlargement 34 at the left end of thesleeve. The enlargement 34 receives a ring 35 (Figs. 6 through 10) whichhas holes 35 for receiving the ends of pin 32 which is retained by awire band 31 received by a groove 38 in ring 35 and having one end whichis bent inwardly as shown as 31a (Fig. 2) and is received by hole 38b(Figs. Sand 9). Ring 35 provides a stop lug 33 for engagement by a stoplug 4t pro vided by a nut 4| (Figs. 11-13) having internal helicalthreads 42 cooperating with the external helical threads 43 of sleeve3|. The not 4| is normally retained in the position shown in Fig. 2 withits stop lug 49 engaging stop lug 39 of ring 35 by a spring 44 having anend portion 45 which is received by a groove 45g in the enlargement 34of screw sleeve 3| and having a hook 45 engageable with the left face ofsleeve 3| as shown in Fig. 2. The other end 41 of spring 44 is receivedby a hole 48 in nut 4|, as shown in Fig. 2.

The spring 44 operates as a torsion spring and as a tension spring toassist in returning the nut 4| to normal position. I

Nut 4| provides a hole 49 for receiving a flange 53 of a plunger 5|enclosed by a cup 52 (Fig. 1), the lower edge of which is received by acounterbore 53 in nut 4| (Fig. 13); and the cup 52 encloses a spring 54confined between the upper end of the cup and the flange 50 of plunger5|. Normally the plunger does'not engage the sleeve 3| because it isprevented from doing so by a wire 55 which is passed through a holeinthe upper end of the plunger and is bent around so as to rest upon theupper end of the cup. Nut 4| is provided with concentric cylindrical surfaces 56,51 and 58.

The assembly (Fig. 14) comprises a ring 5| having internal longitudinalsplines 62 adapted to fit between the teeth 12 of a pinion H! which isjournaled on the shaft 28 (Fig. l) and which has a tubular extension Hwhich is received by an internal, annular flange 64 of a sleeve 63 whichis permanently joined to the ring 6|. Sleeve 63 is provided with asurface 68 which fits around the surface 58 of nut 4| and with a surface61. of the same diameter as the surface 51 of nut 4|, and with a surface66 of the same diameter as the surface 55 of nut 4|.

The nut 4| and the sleeve 63 are adapted to be coupled by a torquetransmitting spring 80 which is retained endwise by a cover 8| having aninternal flange 82 engaging the rightend of the ring BI and having itsother end formed into a groove 83 provided by nut 4|. The normalinternal diameter of coils of spring 80 is slightly greater than thediameters of surfaces 51 and 61 and is slightly less than the diametersof the surfaces 56 and 66. Therefore, end turns of spring 89 grip thenut 4| and the sleeve 63.

The location of pinion 10 relative to the sleeve 63 is maintainednormally by a spring I3 confined under compression between the left endfaces of the teeth of pinion 10 and the flange 64 of sleeve 63 which thespring 13 urges against a wire split ring 74 snapped into a groove ofthe pinion extension 1|.

Rotation of the shaft 28 in the proper direction effects, through thescrew and nut connection, axial movement of the pinion lil into position13 of full engagement with the flywheel gear 29 in which position thepinion engages a washer 9|) bearing against a washer 9| and the latterengaging the left end faces of two half washers 92 and 93 received by anannular groove in shaft 28 and retained therein by a washer 94 having aflange 95 which surrounds the washers. A spacer 96 located betweenwasher 94 and a finished surface 91 of the housing extension 21 retainsthe washer 94 in position for retaining washers S2 and 93. The thrustwhich Washer 51!! receives is transmitted through the washer 9| to thehalf washers E2 and 93 and to the shaft 28.

After the pinion has been moved by rotation of the shaft 28 intoposition 10', the transmission of torque to thepinion for the purpose ofcranking the engine begins to build up. Full torque is not appliedimmediately because the spring '80 must first constrict around thesurfaces 5! and 61 respectively, of the nut 4| and the sleeve I53. Thisconstriction of the spring 80 tends to cushion the shock of the torquetransmission to the pinion because, as the spring 80 is constricted, thetorque increases from a relatively low value to a value sufficient tocause the pinion to rotate the engine gear.

In case the end faces of the pinion teeth abut the end faces of theengine gear teeth before meshing, right movement of pinion 70 ismomentarily arrested but the nut 4| and the sleeve 53 continue theirright movement and additionally compress the spring 13 therebypreventing the rapid increase in pressure applied by the pinion teeth tothe engine gear teeth that would occur if this yielding action were notused. This results in rotation of the pinion with respect to the enginegear when-the relatively low torque required of spring 86 is developedwhereupon, registration having been effected, the spring 13 will snapthe pinion 10 into partial enmeshment with the flywheel gear andthereafter motion of the pinion T9 continues until it arrives atposition 10'.

The starting motor cranks the engine; and, when the latter becomesself-operative and tends to drive the pinion faster than it can bedriven by the starting motor, the pinion is automatically demeshed dueto the nut and screw connections between it and the motor. Thisdemeshing movement is assisted by the spring 44 and has beenadditionally stressed torsionally and tensionally when the pinionengages.

In case of a false start, meaning one in which the engine attempts tobecome self -operative but fails and stops, the pinion is not demeshedfrom the flywheel gear but continues to maintain the connection betweenthe starting motor and the engine thereby avoiding the necessity ofreleasing the starter switch and waiting for the starting motor shaft tobecome stationary before repeating the starting operation. This featureis provided for by the plunger 5| carried by the nut 4!. As the nut 4|is automatically threaded along the screw 3|, the plunger 5| rides alongone of the helical threads of the screw 3| indicated at 43x (Fig. 18)and drops in past abutment 43y and down upon a flat surface 432 (Fig.20), thereby locking the nut 4| in a position corresponding to which thepinion occupies at position 16'. In case of a false start, the rotatingspeed attained by the nut 4| is insufficient to cause the plunger 5| tofly out by centrifugal force which is of such low value that it does notovercome the spring 54. Since there is no demeshment of the pinion, thecar driver continues to maintain closure of the starter control switchuntil the engine becomes self-operative. A false start occurringparticularly in cold weather, is usually characterized by the firing ofpart only of the engine cylinders. Each irregular explosion causes theengine to attempt to drive the pinion at a high speed. The drivingtorque which the engine applies to the pinion at irregular intervals isnot transmitted to the nut 4| and from. the nut to the screw 3| throughthe plunger 5! because the torque transmitting clutchslips and allowsthe pinion to overrun the nut when the engine applied torque tends tobecome excessive. Therefore the clutch serves to protect the plunger 5|and the engaged wall of the abutment 43y of the plunger receiving recessof screw 3| by preventing transmission of excessive torque from thepinion to the nut.

The retraction by the action of centrifugal 1 force, of the detentplunger51 from abutment 432/ of a screw thread 43x (Fig. 20) isdependent upon the attainment of a certain speed of the motor armatureshaft 28. The instant the eugine becomes self-operative, the speed atwhich the pinion is driven by the engine initially will be of such valuethat the clutchwill overrun due to the inertia of the motor armatureshaft and parts directly connected therewith, including the motorarmature, the screw sleeve 3 1v aud'the nut 41, and due to the limitedcapacity of the clutch to transmit torque in the reverse direction.Because the clutch overruns when the engine fires, torque is notimmediately transmitted from the pinion 70 to the nut 41. Between theinstant the engine fires and the instant the nut 41 attains a speedsufficient to efiect retraction of plunger 51, there is an appreciablelapse of time during which the nut 41 is rapidly accelerated by thestarting motor which has been relieved of the engine cranking load andwhich, under normal conditions, remains connected with a current sourcesince the car driver is not apt to release the starter switch theinstant the engine fires. As the motor armature shaft 28 is acceleratedby torque produced by the starting motor, assisted by the limited torquetransmitted by the clutch when it overruns, the slippage of the clutchdecreases and the speed of the screw sleeve 31 and nut 41 increasesfinally to a value such that centrifugal force acting on the plunger 51overcomes the force of the spring 54 and the plunger 51 is retractedfrom the abutment 43y so that the pinion 72 will be demeshed from enginegear 92 by virtue of engine operation. I it happened that the starterswitch were opened before the speed of nut 41 had reached a value suchthat detent plunger 51 is retracted, said speed value would eventuallybe attained by the limited torque transmitted by the clutch from thepinion to the nut.

Thus the clutch, which yieldingly transmits rotary motion between thenut 41 and the pinion 70 to overcome gear tooth abut ent when requiredand to efiect a gradual application of torque to effect engine crankingafter the pinion is fully meshed with the engine gear 29 serves also toprotect the plunger 51 from damage either in case of a false start or atthe instant of actual self-operation of the engine by preventinginstantaneous transmission of torque from the pinion 70 to the nut 41;and, because this clutch initially overruns, time is provided foracceleration of nut 41 by torque developed by the starting motor and theoverrunning clutch, or by the overrunning torque of the clutch alone.Regardless of the speed of the pinion when driven by the operativeengine, the speed of the armatare when the detent plunger is retractedis always the same.

[The instant the engine becomes self-operative, the engine-appliedtorque may initially be of such value that the clutch will slip; but, aspinion speed increases, during further operation of the engine, slippageof the clutch decreases and the nut is driven by the pinion for aninstant at such speed that the centrifugal force spring 54 so that theplunger end moves above surface 432 and abutment 43y, thereby permittingdemeshment of the pinion.

Thus the clutch, which yieldingly transmits rotary motion between thenut 5| and the pinion to overcome gear tooth abutment when required andto effect a gradual application of torque to effect engine crankingafter the pinion is fully meshed with the engine gear 2-9, serves alsoto limit the transmission of engine applied torque to the nut at theinstant of firing thereby protecting the plunger 5| from damage eitherin case of a false start or at the beginning of actual self-operation ofthe engine] While the embodiment of the present invention as hereindisclosed, constitutes a preferred form, it is to be understood thatother forms might be adopted.

What is claimed is as follows:

1. An engine starter drive comprising a tubular screw shaft adapted tobe mounted on a starting motor shaft and to be connected therewith, apinion movable axially along the motor shaft into mesh with an enginegear, a nut threadedly connected with the screw shaft, means foryieldingly transmitting rotary motion from the nut to the pinion, meansfor yieldingly transmitting motion axially from the nut to the pinion inthe direction to mesh the pinion with the engine gear, means fornonyieldingly transmitting motion from the nut to the pinion in thedirection to retract the pinion from the engine gear,

. acting on plunger 5! is sufficient to overcome the 1 stops providedrespectively by the screw shaft and the nut which are engaged uponrotation of the nut in the direction to retract the pinion, a helicaltorsion spring surrounding the sores shaft and connected with the nutand screw shaft for retaining the stop of the nut normally 'agement withthe stop of the screw shaft by the pinion is located a definite distancefrom the engine gear, said screw shaft having a non-threaded portion ofdiameter less than the outside diameter of the screw threads between itsthreaded portion and its stop, a latching plunger guided by the nut formovement transversely thereof, a spring opposing movement of the plungerby centrifugal force, said plunger being located on the nut for movementby the nut from a normal position adjacent the nonthreaded portion ofthe screw shaft to a position engaging a thread of the screw shaft onlyafter the pinion has partially meshed with the engine gear, said threadof the screw shaft having a recess for receiving the plunger afterfurther meshing of the pinion, said second spring urging the plungerinto said recess, and means preventing engagement of the plunger withthe non-threaded portion of the screw shaft.

2. An engine starter drive comprising a screwshaft connectible with astarting motor shaft and having a non-threaded portion of diameter lessthan the outside diameter of the screw threads, a nut threaded on thescrew shaft and having a transverse hole the inner end of which alignswith the non-threaded portion of the screw shaft in the normal positionof the nut, a latching plunger received by said hole, a springsurrounding the plunger and urging it toward the screw shaft, a springretainer attached to the nut and enclosing the spring and providing anopening through which the outer end of the plunger extends, a pinsecured to the outer end of the plunger to engage the retainer toprevent movement by the spring of the inner end of the plunger againstthe non-threaded portion of the screw shaft, the hole in the nut beingso located that the inner end of the plunger will engage the outersurface of a thread of the screw shaft as the nut is threadedtherealong, a pinion movable axially along the motor shaft into meshwith an engine gear, means for yieldingly transmitting motion axiallybetween the nut and pinion, means for yieldingly transmitting rotarymotion between the nut and pinion, the thread engaged by the plungerhaving a recess which receives the inner end of the member when the nuthas moved along the screw shaft into a position for effecting meshing ofthe pinion with the engine gear, said recess providing an abutmentengaged by said member to prevent piniondemeshing movement of the nutuntil a predetermined rotation speed thereof has been attained.

PAUL L. SCHNEIDER. DENNIS W. NIGHBERT. HAROLD J. CROMWELL.

REFERENCES CITED The following references are of record in the file ofthis patent or the original patent:

UNITED STATES PATENTS

